This invention relates to real time optical wavefront synthesis.
Optical wavefront synthesis in real time is highly desirable and has many applications. One application is for commercial laser ranging systems for general non-contact metrology, for example, for surface deformation measurement, precision machining systems and topographic mapping systems. Another application is in laser scanning devices such as supermarket bar code readers, flying spot scanners for printed circuit board inspection and machine vision systems. Laser printing devices and smart optical alignment systems are other applications of wavefront synthesis. Heretofore, the above applications utilized electro-mechanical equipment for steering the laser beam. Such electro-mechanical steering systems have inherent limitations on the speed of steering and adjustment of the optical wavefront.
U.S. Pat. No. 3,691,483 to Klein teaches a phased array laser source capable of scanning a laser beam non-mechanically. In particular, Klein teaches the use of explicit optical phase shifters and a special dual function laser structure requiring separate laser drive current and phase shift control lines. The injection power to the array in Klein is reduced because of losses in the phase shifters. The phase shifters also induce photo refractive instabilities. The Klein apparatus is strictly open loop with no provision to compensate for de-phasing caused by thermal or mechanical distortion effects.